Vapor filled electronic device



J. J. MASON VAPOR FILLED ELECTRONIC DEVICE March 23, 1948,

( Filed 001:. 26, 1946 INVENTOR JTJ'. M/QSO/V VIII/671114 W M J ,,,P:/- l? w I w I Patented Mar. 23, 1948 VAPOR FILLED ELECTRONIC DEVICE Julien J. Mason, Montclair, N. J., assignor to Westinghouse Electric Corporation, East Pittsburgh,'Pa., a corporation of Pennsylvania Application October 26, 1946, Serial No. 705,883

Claims. (Cl. 250-275) This invention relates to a vapor filled electronic device, and more particularly to such device having a liquid electrode and of the character generally identified as ignitrons.

In devices of the type indicated, the liquid electrode is of a recurringly vaporizable and condensible material, of which mercury is the substance usually employed. It has been found that the usual constructions of lgnitrons although satisfactory for moderate or low voltage use are not satisfactory at high voltages, such as 30 or 40 kv. However, the development of ignitron tubes for such high voltage service is very desirable. Investigation and study of the problem develops cause for the inability of the usual ignitron to function properly beyond the moderate range of voltages to be due to condensation of the mercury markedly decreasing the ability of the ignitron to stand off spurious high voltage discharges. It has been found that mercury deposited on the glass walls in regions of high electric field, droplets of mercury falling through such regions of high field, and droplets splashing into the pool cathode all may cause the ignitron to prefire or arc-back at voltages well below those at which it would operate in the absence of these specified, and other, detrimental occurrences. Even the presence of mercury droplets on some conducting surface of an ignitron, especially one in which the parts are closely spaced, may provide a point of sufficient field concentration to cause field emission and premature breakdown. It consequently becomes a problem of fundamental importance for a high voltage ignitron, to control the condensation of the mercury or other recurringly vaporizable and condensible material used as the cathode.

The primary object of the invention. accordingly is to provide for control of the condensation product in an ignitron or the like.

More specifically; an object of the invention is to provide meansfor restricting the condensation product to a region where it cannot deleteriously affect the ability of the ignitron to hold of! spurious high voltage discharges.

A further object of the invention is to isolate thecondensation and the returning product of condensation from the discharge portion of the device.

Again, an object of the invention is to provide a chamber substantially at cathode potential wherein the condensation is concentrated and promoted.

Other objects of the invention will appear to those skilled in the art to which it appertains i asthe' description proceeds, both by'direct reference thereto and by implication from the context.

Referring to the accompanying drawing in which like numerals of reference indicate similar parts throughout the several views;

Figure 1 is a vertical cross-section of an ignitron embodying my invention; and

Figures 2 and 3 are cross-sections thereof on lines II-II and IIL-III respectively.

In the specific embodiment of the invention illustrated in said drawing, the reference numeral 58 designates a generally cylindrical sealed container or which an upper andouter portion is a glass body portion II the lower cylindrical margin of which is here shown as sealed to the upper rim of a metal cup-shaped bottom header l2. A novel feature of the present construction resides in the provision of a re-entrant cylindrical inner wall It as a continuation of and integral with the uppermost part of the outer body portion I! whereby inner wall i3 is coaxial within the outer body portion providing a hollow space between the body portion and wall closed at the top thereof and open within the container toward the bottom thereof. The inner cylindrical wall 13 is longer in the present showing than the outer glass body portion l l and is likewise glass thereby providing an inner glass portion projecting from above into the metal cup-shaped header l2 but spaced and insulated therefrom. The cathode comprises a pool [4 of mercury or other reconstructable vaporizable material contained in said metallic bottom header at a level well below the lower edges of both the inner and outer glass portions above described.

Anode I5 is herein illustrated as of continuous annular channel formation about an axis with the channel opening directed longitudinally of that axis, and having a central hole or passage axially therethrough; it is comparable in shape to a doughnut-cutter with a washer-like end wall it and inner and outer collar-like flanges ll, l8 both projecting in the same direction from the end wall it. As disposed in the present assembly,

the anode is smaller than and coaxial with and within the header l2, andhas its end wall-l6 directed toward the top surface of pool I4 substantially parallel thereto, and proximate to but spaced thereabove. Outer flange l3 is sealed at its upper peripheral edge to the lower ed e of a glass tubular flare [9 extending coaXially within said cylindrical wall iii. The upper end of said tubular flare I9 is made integral with a smaller glass tube 20 which is coaxial therewith and which in part depends into the tubular flare and in part projects upwardly therefrom. Lower end of the inner glass tube 20 is sealed with a cupshaped header 2!. It may now be called to attention that none of the several seals above-described is opposite any other of the seals, and that the seal for the inner flange of the anode is stepped above the seal for the outer flange thereof and that the seal forthe header 2,! on the inne glass tube 23! is stepped above the seal for the inner flange of the anode. This arrangement is conducive to making the seals most conveniently and in avoiding likelihood of electrical break-down across gaps between seals.

Header 2| on the inner glass tube 20 supports an ignitor 22 which depends coaxially therefrom to the pool M where it has a suitable tip of reduced diameter and appropriate semi-conductive character for initiating a spark or discharge in the container and from. the pool surface. The ignitor 22 is connected through header 2! to a suitable lead-in wire 23 which extends downwardly thereto within the inner glass tube 251. Lead-in connection to the anode is made by a metallic sleeve 24, secured as by ring 25 soldered within the anode channel.- Said sleeve 24 extends coaxially between inner Wall 13 of the glass housing and the tubular flare, projecting above the housing and having a suitable vane or other heatradiator'26 thereon. As said sleeve 24 is heat conductive and is conducting heat from the anode, it will serve the beneficial purpose of radiating some of that heat to the pocket 36 formed between flare l9 and inner tube 23 to prevent condensation of mercury in that pocket.

Within the container, as an essential feature of the present invention, is a shield 21, here shown in the form of a cup preferably of metal and with its bottom wall immersed in the pool l4. Pool level is maintained inside and outside of said cup'2l by provision of a plurality of holes 28 in the bottom of the cup. The important feature of the shield 2-! is that it provides a side Wall, here chosen as cylindrical, said side wall of the shield extending coaxially from within the pool I4 upward well toward the top of the space between inner and outer walls of the cylindrical glass. body portion ll of the container, and thereby divides that space into an outer chamber 29 between said shield wall and the outer wall of the body portion.

Inasmuch as the particular embodiment of the device is cooled at its exterior, as by an air blast on the outside wall from a position directly below the bottom of the device, outside wall of the body portion will be considerably cooler than inside wall l3 and chamber 29 next thereto will function as a condensing chamber and the condensed pool material will appear upon and trickle down the'inside surface of said outside wall back into the pool. Location of inner wall l3 within the outer wall, protects it from the cooling blast, and since it remains hot there is substantially no condensation on that wall. Similarly the inner flange of the anode is protected and its glasssupporting flare I9, as well as the associated innertube 20, ignitor 22 and ignitor header 2| all are in heated regions as distinguished from the much lower temperature of the outer wall and chamber 29. Consequently, mercury condensation is restricted to the said outer wall, which is the coolest surface, and to the next adjacent cooled or condensation chamber 29. This region of mercury condensation is eifectively shieldedfrom' the anode and the discharge region of the device byv means or. the cylindrical 4 wall of shield cup 21. Thus the condensation is effectively shielded from the high electric fields in the region of active discharge.

The specific embodiment of the invention de scribed is' particularly for air-cooled radar pulse modulation, and some of the unconventional features are the result of unusual requirements placed upon it. Thus, in order to obtain a high breakdown voltage between the anode and the pool cathode and at the same time keep the tube voltage drop to a. minimum and provide quick transfer of the ignited arc to the anode, very close anode to cathode spacing is used rather than the grids or bafiies of more conventional rectifier tubes. However, it should be pointed out thatmy invention may be applied equally well to pool typetubes of more conventional design employing water cooling jackets and with or without grids or baffles. Also it is not necessary that the anode be restricted to such metals that can be properly sealed to glass, and any suitable anode material, such as the more conventional carbon or graphite, may be suspended-from an appropriate lead.

I claim:

1. An electronic device comprising a sealed container having a recurringly vaporizable and condensible liquid cathode therein gravitating to the bottom thereof, an anod within said container above the cathode, and a cup-shaped. shield the bottom wall whereof is submerged in the cathode and the side wall whereof projects-above the cathode between said anode and the outer side wall of the container, said'cup-shaped shield having holes therein below the surface level of the cathode for equalizing level of the said cathode inside and outside of said shield, and means at the underside of said bottom wall of the shield constituting the sole support for said shield.

2. An electronic device comprising a sealed container having a re-entrant inner wall extending from the upper end of an outer.wall',..and said container having a bottom wall extending to and closed with respect to said outer wall, an anode carried by said inner wall in spaced relation to said bottom wall, a vaporizable poolcathodegravitationally supported on said bottom wall below said anode, a shield extending-from: said cathode above said anode and between the outer and inner walls of said container, and means entirely within said pool cathode projecting upwardly from said bottom wall of thecontainer and constituting the sole support for said;shield. 3. An electronic device comprising a container having a bottom and an outer side'walLa reentrant inner side wall joined at its upper. end to said outer side wall, an annular channel-shaped anode providing upstanding inner and outer flanges of which the outer flange isof less height than the inner flange and is sealed to saidinner wall of the container, a glass flare sealed to the inner flange of said anode at a level higher than the said sealing ofthe outer flange, and a recurringly-vaporizable and condensible liquid cathode at the bottom of said container belowsaidanode.

4. An electronic device comprising a-container having a bottom and an outer side Wall,-a reentrant inner side Wall joined atits upper end to said outer wall, an annular channel-shaped anode providing upstanding inner and outer flanges of which the outer flange is of less height than the inner flange and is sealed to said inner wall of the container, a hollow glass flare sealed to the inner flange of said anode at'a level higher than the said sealingxof the outer flange, an inner tube in said flare, a header sealed to the lower end of said inner tube at a level higher than the sealing of the anode to the flare, whereby said seals are successively higher each to the next one before, and a recurringly vaporizable and condensible liquid cathode at the bottom of said container below said anode and header.

5. An electronic device comprising a sealed container having a recurringly vaporizable and condensible cathode therein gravitating to the bottom thereof, an anode coaxial to and within said container and above the cathode, an ignitor projecting coaxially through said anode and dipping into said cathode, and a shield entirely around and spaced radially from said anode and within and spaced radially from the side wall of said container for forming a condensing cham- 6 ber between said wall and shield, said shield having its lower end submerged in the cathode.

JULIEN J. MASON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 10 Number Name Date 1,824,755 Bouwers Sept. 22, 1931 2,396,294 Spencer Mar. 12, 1946 FOREIGN PATENTS 5 Number Country Date 307,272 Germany Aug. 23, 1917 

